Opinions vary concerning how big you have to grow before a SAN becomes viable. Tom Major, vice president of IP Storage at Boulder, Colo.-based LeftHand Networks, says anyone with fewer than 20 servers or so would be better off sticking with direct-attached storage (DAS).

"Up to 20 servers should be reasonably manageable unless you have large growth expectations," he explains. "Beyond that, shared storage becomes more viable."

Rather than setting the bar based on servers, Joe DeRosa of Maxtor estimates that a 3TB minimum is probably needed before a SAN becomes viable.

"A Storage Area Network incurs big upfront costs," says DeRosa. "You need to have a tremendous amount of storage in use to justify the expense."

Related Articles

In support of this opinion, he quotes Gartner Group figures that show 75 percent of the disks currently existing in the enterprise are still on DAS. For most, it seems, the price tag is a little hefty when it comes to a SAN with its attendant Fibre Channel (FC) switches, storage arrays, and host bus adapters (HBAs).

You don't have to be a Fortune 500 company to adopt a Fibre Channel (FC) SAN, though.

Take the case of Denver Health Hospital and Medical Center. This organization services 20,000 admissions and 600,000 outpatient visits annually. During the late 1990s, it experienced an explosion in its server population — from six servers in 1996 to 97 in 1999. All storage was direct-attached at that point, residing mainly on a wide range of operating systems.

"We were running out of data center space, couldn't manage our storage effectively, and suffered from severe underutilization on many servers," says Jeff Pelot, CTO of Denver Health. Denver Health's SAN consists of EMC CLARiiON boxes (3TB) along with Brocade switches. Despite the high cost, the hospital perceived value on its investment due to greater manageability in its environment.